In certain rats, black fur (B) is dominant over white fur (b). If two rats, both heterozygous (Bb) for fur color, are mated, their offspring would be expected to have

Sickle cell anemia results from a gene mutation that causes abnormalities in red blood cells. The sickle-cell gene is more common in tropical areas, and the individual who is heterozygous for the gene (Ss) has increased resistance to malaria. If two individuals heterozygous (Ss) for the sickle-cell gene have offspring, what percent of their offspring are expected to be heterozygous?

In a certain variety of chicken, the genes for black feather color and the genes for white feather color are codominant. This condition produces

Color-blindness, resulting from a sex-linked trait, is more common in males than in females because

Hemophilia is a sex‐linked, recessive trait. Which of the following describes the probability of hemophilia in the offspring of a man who does not have hemophilia and a woman who is a heterozygous carrier?

When an organism has more than 10 fingers or toes, the condition is known as polydactylism. Although polydactylism is rare, it is a dominant trait. If two cats that are heterozygous for polydactylism mate and have a litter with a total of 12 kittens, how many of them would you expect to have more than 10 fingers or toes?

In humans, having freckles (F) is dominant to not having freckles (f). Having a cleft chin (C) is also dominant to not having a cleft chin (c). Which statement is true of the offspring of a cross between parents that are both heterozygous for both traits (FfCc)?

A population of crabs living on a sandy beach exhibits three colors: dark brown, light brown, and speckled. The genotypes for these colors are BB for dark brown, bb for light brown, and Bb for speckled. If a dark brown crab were crossed with a light brown crab, what would be the probable phenotypic ratio of their offspring?

A gardener crossed a plant with red flowers with a plant that had white flowers. The offspring plants had pink flowers. What is the most likely genetic reason for these differences in color?

Alleles for the A and B blood cell antigens are codominant. The condition where no antigens are present on the blood cells (type O blood) is a recessive trait. Which set of parents can most likely produce a child with type O blood?

One of the parents of a child has phenylketonuria (PKU), which is caused by recessive alleles. The other parent does not have the PKU alleles. What is the chance that the couple will have a child with phenylketonuria?

Hitchhiker's thumb (H) is dominant to no hitchhiker's thumb (h). A woman who does not have hitchhiker's thumb marries a man who is heterozygous for hitchhiker's thumb. What is the probable genotypic ratio of their children?

This diagram shows a pedigree for a recessive genetic disorder.

What is the genotype of individual 6?

This diagram shows a diploid cell with two pairs of homologous chromosomes.

Due to independent assortment, what is the possible genetic make-up of gametes produced by this organism?

The table lists the trials for fruit color where allele R exhibits incomplete dominance over allele R'.

Heterozygous fruit have orange phenotypes. What percent of offspring are expected to have an orange phenotype if the parent plants are orange (RR') and yellow (R'R')?

Mendel hypothesized that reproductive cells have only one factor for each inherited trait. This hypothesis is supported by which observation?

A human baby boy inherits a recessive allele from his mother. In which circumstance would he most likely show the trait coded for by the recessive allele?

A. The baby inherits the dominant allele from his father.

B. The allele is on an autosomal chromosome and the baby is a twin.

C. The allele is on the X chromosome.

D. The allele is on the Y chromosome.